He was already at that time scattering germs of ideas, with the intention of taking them up later on and experimenting on them, or, if time should fail him, willingly offering them to any attentive scientist. These studies on beer had brought him back to his former studies, to his great delight.
“What a sacrifice I made for you,” he could not help saying to Dumas, with a mixture of affection and deference, and some modesty, for he apparently forgot the immense service rendered to sericiculture, “when I gave up my studies on ferments for five whole years in order to study silkworms!!!”
No doubt a great deal of time was also wasted by the endless discussions entered into by his scientific adversaries; but those discussions certainly brought out and evidenced many guiding facts which are now undisputed, as for instance the following--1. Ferments are living beings. 2. There is a special ferment corresponding to each kind of fermentation. 3. Ferments are not born spontaneously.
Liebig and his partisans had looked upon fermentation as a phenomenon of death; they had thought that beer yeast, and in general all animal and vegetable matter in a state of putrefaction, extended to other bodies its own state of decomposition.
Pasteur, on the contrary, had seen in fermentation a phenomenon correlative with life; he had provoked the complete fermentation of a sweet liquid which contained mineral substances only, by introducing into it a trace of yeast, which, instead of dying, lived, flourished and developed.
To those who, believing in spontaneous generation, saw in fermentations but a question of chance, Pasteur by a series of experimental proofs had shown the origin of their delusion by indicating the door open to germs coming from outside. He had moreover taught the method of pure cultures. Finally, in those recent renewals of old quarrels on the transformations into each other of microscopic species, Pasteur, obliged by the mycoderma vini to study closely its alleged transformation, which he had himself believed possible, had thrown ample light on the only dark spot of his luminous domain.
“It is enough to think,” writes M. Duclaux concerning that long discussion, “we have but to remember that those who denied the specific nature of the germ would now deny the specific nature of disease, in order to understand the darkness in which such opinions would have confined microbian pathology; it was therefore important that they should be uprooted from every mind.”